Method for transmitting data in a communication system and device therefor

ABSTRACT

The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for transmitting, by a user equipment (UE), data in a wireless communication system, the method comprising: receiving a first uplink grant for a logical channel group (LCG) and a first LCG indicator of the LCG; generating a Medium Access Control Protocol Data Unit (MAC PDU) containing a data of only the LCG indicated by the first LCG indicator; and transmitting the MAC PDU using the first uplink grant.

This application claims the benefit of the U.S. Patent Application No.62/358,147 filed on Jul. 4, 2016, which is hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a wireless communication system and,more particularly, to a method for transmitting data in a communicationsystem and a device therefor.

Discussion of the Related Art

As an example of a mobile communication system to which the presentinvention is applicable, a 3rd Generation Partnership Project Long TermEvolution (hereinafter, referred to as LTE) communication system isdescribed in brief.

FIG. 1 is a view schematically illustrating a network structure of anE-UMTS as an exemplary radio communication system. An Evolved UniversalMobile Telecommunications System (E-UMTS) is an advanced version of aconventional Universal Mobile Telecommunications System (UMTS) and basicstandardization thereof is currently underway in the 3GPP. E-UMTS may begenerally referred to as a Long Term Evolution (LTE) system. For detailsof the technical specifications of the UMTS and E-UMTS, reference can bemade to Release 7 and Release 8 of “3rd Generation Partnership Project;Technical Specification Group Radio Access Network”.

Referring to FIG. 1, the E-UMTS includes a User Equipment (UE), eNode Bs(eNBs), and an Access Gateway (AG) which is located at an end of thenetwork (E-UTRAN) and connected to an external network. The eNBs maysimultaneously transmit multiple data streams for a broadcast service, amulticast service, and/or a unicast service.

One or more cells may exist per eNB. The cell is set to operate in oneof bandwidths such as 1.25, 2.5, 5, 10, 15, and 20 MHz and provides adownlink (DL) or uplink (UL) transmission service to a plurality of UEsin the bandwidth. Different cells may be set to provide differentbandwidths. The eNB controls data transmission or reception to and froma plurality of UEs. The eNB transmits DL scheduling information of DLdata to a corresponding UE so as to inform the UE of a time/frequencydomain in which the DL data is supposed to be transmitted, coding, adata size, and hybrid automatic repeat and request (HARQ)-relatedinformation. In addition, the eNB transmits UL scheduling information ofUL data to a corresponding UE so as to inform the UE of a time/frequencydomain which may be used by the UE, coding, a data size, andHARQ-related information. An interface for transmitting user traffic orcontrol traffic may be used between eNBs. A core network (CN) mayinclude the AG and a network node or the like for user registration ofUEs. The AG manages the mobility of a UE on a tracking area (TA) basis.One TA includes a plurality of cells.

Although wireless communication technology has been developed to LTEbased on wideband code division multiple access (WCDMA), the demands andexpectations of users and service providers are on the rise. Inaddition, considering other radio access technologies under development,new technological evolution is required to secure high competitivenessin the future. Decrease in cost per bit, increase in serviceavailability, flexible use of frequency bands, a simplified structure,an open interface, appropriate power consumption of UEs, and the likeare required.

SUMMARY OF THE INVENTION

The object of the present invention can be achieved by providing amethod for transmitting, by a user equipment (UE), data in a wirelesscommunication system, the method comprising: receiving a first uplinkgrant for a logical channel group (LCG) and a first LCG indicator of theLCG; generating a Medium Access Control Protocol Data Unit (MAC PDU)containing a data of only the LCG indicated by the first LCG indicator;and transmitting the MAC PDU using the first uplink grant.

In another aspect of the present invention provided herein is an UEoperating in wireless communication system, the UE comprising: a radiofrequency (RF) module configured to transmit/receive signals to/from anetwork; and a processor configured to process the signals, wherein theprocessor is configured to: control the RF module to receive a firstuplink grant for a logical channel group (LCG) and a first LCG indicatorof the LCG, generate a Medium Access Control Protocol Data Unit (MACPDU) containing a data of only the LCG indicated by the first LCGindicator, and control the RF module to transmit the MAC PDU using thefirst uplink grant.

Preferably, the first uplink grant and the first LCG indicator arereceived through a Downlink Control Information (DCI) included in aPhysical Downlink Control Channel (PDCCH).

Preferably, the DCI further includes a second uplink grant for anotherLCG and a second LCG indicator of the another LCG.

Preferably, the first uplink grant and the first LCG indicator arereceived through a downlink MAC PDU included in a Physical DownlinkShared Channel (PDSCH).

The method further comprising receiving a Downlink Control Information(DCI) indicating the PDSCH through a Physical Downlink Control Channel(PDCCH).

Preferably, the first uplink grant and the first LCG indicator areincluded in the downlink MAC PDU as a MAC control element (CE).

Preferably, the MAC CE further includes a second uplink grant foranother LCG and a second LCG indicator of the another LCG.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention.

FIG. 1 is a diagram showing a network structure of an Evolved UniversalMobile Telecommunications System (E-UMTS) as an example of a wirelesscommunication system;

FIG. 2 is a block diagram illustrating network structure of an evolveduniversal mobile telecommunication system (E-UMTS), and FIG. 2B is ablock diagram depicting architecture of a typical E-UTRAN and a typicalEPC;

FIGS. 3a and 3b are diagrams showing a control plane and a user plane ofa radio interface protocol between a UE and an E-UTRAN based on a 3rdgeneration partnership project (3GPP) radio access network standard;

FIG. 4 is a diagram of an example physical channel structure used in anE-UMTS system;

FIG. 5 is a diagram for a general overview of the LTE protocolarchitecture for the downlink.

FIG. 6 is a conceptual diagram for dual connectivity between a MasterCell Group (MCG) and a Secondary Cell Group (SCG).

FIG. 7 is a diagram for transmitting data according to an embodiment ofthe present invention.

FIG. 8 is a block diagram of a communication apparatus according to anembodiment of the present invention

DETAILED DESCRIPTION OF THE INVENTION

Universal mobile telecommunications system (UMTS) is a 3rd Generation(3G) asynchronous mobile communication system operating in wideband codedivision multiple access (WCDMA) based on European systems, globalsystem for mobile communications (GSM) and general packet radio services(GPRS). The long-term evolution (LTE) of UMTS is under discussion by the3rd generation partnership project (3GPP) that standardized UMTS.

The 3GPP LTE is a technology for enabling high-speed packetcommunications. Many schemes have been proposed for the LTE objectiveincluding those that aim to reduce user and provider costs, improveservice quality, and expand and improve coverage and system capacity.The 3G LTE requires reduced cost per bit, increased serviceavailability, flexible use of a frequency band, a simple structure, anopen interface, and adequate power consumption of a terminal as anupper-level requirement.

Hereinafter, structures, operations, and other features of the presentinvention will be readily understood from the embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Embodiments described later are examples in which technicalfeatures of the present invention are applied to a 3GPP system.

Although the embodiments of the present invention are described using along term evolution (LTE) system and a LTE-advanced (LTE-A) system inthe present specification, they are purely exemplary. Therefore, theembodiments of the present invention are applicable to any othercommunication system corresponding to the above definition. In addition,although the embodiments of the present invention are described based ona frequency division duplex (FDD) scheme in the present specification,the embodiments of the present invention may be easily modified andapplied to a half-duplex FDD (H-FDD) scheme or a time division duplex(TDD) scheme.

FIG. 2A is a block diagram illustrating network structure of an evolveduniversal mobile telecommunication system (E-UMTS). The E-UMTS may bealso referred to as an LTE system. The communication network is widelydeployed to provide a variety of communication services such as voice(VoIP) through IMS and packet data.

As illustrated in FIG. 2A, the E-UMTS network includes an evolved UMTSterrestrial radio access network (E-UTRAN), an Evolved Packet Core (EPC)and one or more user equipment. The E-UTRAN may include one or moreevolved NodeB (eNodeB) 20, and a plurality of user equipment (UE) 10 maybe located in one cell. One or more E-UTRAN mobility management entity(MME)/system architecture evolution (SAE) gateways 30 may be positionedat the end of the network and connected to an external network.

As used herein, “downlink” refers to communication from eNodeB 20 to UE10, and “uplink” refers to communication from the UE to an eNodeB. UE 10refers to communication equipment carried by a user and may be alsoreferred to as a mobile station (MS), a user terminal (UT), a subscriberstation (SS) or a wireless device.

FIG. 2B is a block diagram depicting architecture of a typical E-UTRANand a typical EPC.

As illustrated in FIG. 2B, an eNodeB 20 provides end points of a userplane and a control plane to the UE 10. MME/SAE gateway 30 provides anend point of a session and mobility management function for UE 10. TheeNodeB and MME/SAE gateway may be connected via an S1 interface.

The eNodeB 20 is generally a fixed station that communicates with a UE10, and may also be referred to as a base station (BS) or an accesspoint. One eNodeB 20 may be deployed per cell. An interface fortransmitting user traffic or control traffic may be used between eNodeBs20.

The MME provides various functions including NAS signaling to eNodeBs20, NAS signaling security, AS Security control, Inter CN node signalingfor mobility between 3GPP access networks, Idle mode UE Reachability(including control and execution of paging retransmission), TrackingArea list management (for UE in idle and active mode), PDN GW andServing GW selection, MME selection for handovers with MME change, SGSNselection for handovers to 2G or 3G 3GPP access networks, Roaming,Authentication, Bearer management functions including dedicated bearerestablishment, Support for PWS (which includes ETWS and CMAS) messagetransmission. The SAE gateway host provides assorted functions includingPer-user based packet filtering (by e.g. deep packet inspection), LawfulInterception, UE IP address allocation, Transport level packet markingin the downlink, UL and DL service level charging, gating and rateenforcement, DL rate enforcement based on APN-AMBR. For clarity MME/SAEgateway 30 will be referred to herein simply as a “gateway,” but it isunderstood that this entity includes both an MME and an SAE gateway.

A plurality of nodes may be connected between eNodeB 20 and gateway 30via the S1 interface. The eNodeBs 20 may be connected to each other viaan X2 interface and neighboring eNodeBs may have a meshed networkstructure that has the X2 interface.

As illustrated, eNodeB 20 may perform functions of selection for gateway30, routing toward the gateway during a Radio Resource Control (RRC)activation, scheduling and transmitting of paging messages, schedulingand transmitting of Broadcast Channel (BCCH) information, dynamicallocation of resources to UEs 10 in both uplink and downlink,configuration and provisioning of eNodeB measurements, radio bearercontrol, radio admission control (RAC), and connection mobility controlin LTE_ACTIVE state. In the EPC, and as noted above, gateway 30 mayperform functions of paging origination, LTE-IDLE state management,ciphering of the user plane, System Architecture Evolution (SAE) bearercontrol, and ciphering and integrity protection of Non-Access Stratum(NAS) signaling.

The EPC includes a mobility management entity (MME), a serving-gateway(S-GW), and a packet data network-gateway (PDN-GW). The MME hasinformation about connections and capabilities of UEs, mainly for use inmanaging the mobility of the UEs. The S-GW is a gateway having theE-UTRAN as an end point, and the PDN-GW is a gateway having a packetdata network (PDN) as an end point.

FIG. 3 is a diagram showing a control plane and a user plane of a radiointerface protocol between a UE and an E-UTRAN based on a 3GPP radioaccess network standard. The control plane refers to a path used fortransmitting control messages used for managing a call between the UEand the E-UTRAN. The user plane refers to a path used for transmittingdata generated in an application layer, e.g., voice data or Internetpacket data.

A physical (PHY) layer of a first layer provides an information transferservice to a higher layer using a physical channel. The PHY layer isconnected to a medium access control (MAC) layer located on the higherlayer via a transport channel. Data is transported between the MAC layerand the PHY layer via the transport channel. Data is transported betweena physical layer of a transmitting side and a physical layer of areceiving side via physical channels. The physical channels use time andfrequency as radio resources. In detail, the physical channel ismodulated using an orthogonal frequency division multiple access (OFDMA)scheme in downlink and is modulated using a single carrier frequencydivision multiple access (SC-FDMA) scheme in uplink.

The MAC layer of a second layer provides a service to a radio linkcontrol (RLC) layer of a higher layer via a logical channel. The RLClayer of the second layer supports reliable data transmission. Afunction of the RLC layer may be implemented by a functional block ofthe MAC layer. A packet data convergence protocol (PDCP) layer of thesecond layer performs a header compression function to reduceunnecessary control information for efficient transmission of anInternet protocol (IP) packet such as an IP version 4 (IPv4) packet oran IP version 6 (IPv6) packet in a radio interface having a relativelysmall bandwidth.

A radio resource control (RRC) layer located at the bottom of a thirdlayer is defined only in the control plane. The RRC layer controlslogical channels, transport channels, and physical channels in relationto configuration, re-configuration, and release of radio bearers (RBs).An RB refers to a service that the second layer provides for datatransmission between the UE and the E-UTRAN. To this end, the RRC layerof the UE and the RRC layer of the E-UTRAN exchange RRC messages witheach other.

One cell of the eNB is set to operate in one of bandwidths such as 1.25,2.5, 5, 10, 15, and 20 MHz and provides a downlink or uplinktransmission service to a plurality of UEs in the bandwidth. Differentcells may be set to provide different bandwidths.

Downlink transport channels for transmission of data from the E-UTRAN tothe UE include a broadcast channel (BCH) for transmission of systeminformation, a paging channel (PCH) for transmission of paging messages,and a downlink shared channel (SCH) for transmission of user traffic orcontrol messages. Traffic or control messages of a downlink multicast orbroadcast service may be transmitted through the downlink SCH and mayalso be transmitted through a separate downlink multicast channel (MCH).

Uplink transport channels for transmission of data from the UE to theE-UTRAN include a random access channel (RACH) for transmission ofinitial control messages and an uplink SCH for transmission of usertraffic or control messages. Logical channels that are defined above thetransport channels and mapped to the transport channels include abroadcast control channel (BCCH), a paging control channel (PCCH), acommon control channel (CCCH), a multicast control channel (MCCH), and amulticast traffic channel (MTCH).

FIG. 4 is a view showing an example of a physical channel structure usedin an E-UMTS system. A physical channel includes several subframes on atime axis and several subcarriers on a frequency axis. Here, onesubframe includes a plurality of symbols on the time axis. One subframeincludes a plurality of resource blocks and one resource block includesa plurality of symbols and a plurality of subcarriers. In addition, eachsubframe may use certain subcarriers of certain symbols (e.g., a firstsymbol) of a subframe for a physical downlink control channel (PDCCH),that is, an L1/L2 control channel. In FIG. 4, an L1/L2 controlinformation transmission area (PDCCH) and a data area (PDSCH) are shown.In one embodiment, a radio frame of 10 ms is used and one radio frameincludes 10 subframes. In addition, one subframe includes twoconsecutive slots. The length of one slot may be 0.5 ms. In addition,one subframe includes a plurality of OFDM symbols and a portion (e.g., afirst symbol) of the plurality of OFDM symbols may be used fortransmitting the L1/L2 control information. A transmission time interval(TTI) which is a unit time for transmitting data is 1 ms.

A base station and a UE mostly transmit/receive data via a PDSCH, whichis a physical channel, using a DL-SCH which is a transmission channel,except a certain control signal or certain service data. Informationindicating to which UE (one or a plurality of UEs) PDSCH data istransmitted and how the UE receive and decode PDSCH data is transmittedin a state of being included in the PDCCH.

For example, in one embodiment, a certain PDCCH is CRC-masked with aradio network temporary identity (RNTI) “A” and information about datais transmitted using a radio resource “B” (e.g., a frequency location)and transmission format information “C” (e.g., a transmission blocksize, modulation, coding information or the like) via a certainsubframe. Then, one or more UEs located in a cell monitor the PDCCHusing its RNTI information. And, a specific UE with RNTI “A” reads thePDCCH and then receive the PDSCH indicated by B and C in the PDCCHinformation.

FIG. 5 is a diagram for a general overview of the LTE protocolarchitecture for the downlink.

A general overview of the LTE protocol architecture for the downlink isillustrated in FIG. 5. Furthermore, the LTE protocol structure relatedto uplink transmissions is similar to the downlink structure in FIG. 5,although there are differences with respect to transport formatselection and multi-antenna transmission.

Data to be transmitted in the downlink enters in the form of IP packetson one of the SAE bearers (501). Prior to transmission over the radiointerface, incoming IP packets are passed through multiple protocolentities, summarized below and described in more detail in the followingsections:

-   -   Packet Data Convergence Protocol (PDCP, 503) performs IP header        compression to reduce the number of bits necessary to transmit        over the radio interface. The header-compression mechanism is        based on ROHC, a standardized header-compression algorithm used        in WCDMA as well as several other mobile-communication        standards. PDCP (503) is also responsible for ciphering and        integrity protection of the transmitted data. At the receiver        side, the PDCP protocol performs the corresponding deciphering        and decompression operations. There is one PDCP entity per radio        bearer configured for a mobile terminal.    -   Radio Link Control (RLC, 505) is responsible for        segmentation/concatenation, retransmission handling, and        in-sequence delivery to higher layers. Unlike WCDMA, the RLC        protocol is located in the eNodeB since there is only a single        type of node in the LTE radio-access-network architecture. The        RLC (505) offers services to the PDCP (503) in the form of radio        bearers. There is one RLC entity per radio bearer configured for        a terminal.

There is one RLC entity per logical channel configured for a terminal,where each RLC entity is responsible for: i) segmentation,concatenation, and reassembly of RLC SDUs; ii) RLC retransmission; andiii) in-sequence delivery and duplicate detection for the correspondinglogical channel.

Other noteworthy features of the RLC are: (1) the handling of varyingPDU sizes; and (2) the possibility for close interaction between thehybrid-ARQ and RLC protocols. Finally, the fact that there is one RLCentity per logical channel and one hybrid-ARQ entity per componentcarrier implies that one RLC entity may interact with multiplehybrid-ARQ entities in the case of carrier aggregation.

The purpose of the segmentation and concatenation mechanism is togenerate RLC PDUs of appropriate size from the incoming RLC SDUs. Onepossibility would be to define a fixed PDU size, a size that wouldresult in a compromise. If the size were too large, it would not bepossible to support the lowest data rates. Also, excessive padding wouldbe required in some scenarios. A single small PDU size, however, wouldresult in a high overhead from the header included with each PDU. Toavoid these drawbacks, which is especially important given the verylarge dynamic range of data rates supported by LTE, the RLC PDU sizevaries dynamically.

In process of segmentation and concatenation of RLC SDUs into RLC PDUs,a header includes, among other fields, a sequence number, which is usedby the reordering and retransmission mechanisms. The reassembly functionat the receiver side performs the reverse operation to reassemble theSDUs from the received PDUs.

-   -   Medium Access Control (MAC, 507) handles hybrid-ARQ        retransmissions and uplink and downlink scheduling. The        scheduling functionality is located in the eNodeB, which has one        MAC entity per cell, for both uplink and downlink. The        hybrid-ARQ protocol part is present in both the transmitting and        receiving end of the MAC protocol. The MAC (507) offers services        to the RLC (505) in the form of logical channels (509).    -   Physical Layer (PHY, 511), handles coding/decoding,        modulation/demodulation, multi-antenna mapping, and other        typical physical layer functions. The physical layer (511)        offers services to the MAC layer (507) in the form of transport        channels (513).

FIG. 6 is a conceptual diagram for dual connectivity between a MasterCell Group (MCG) and a Secondary Cell Group (SCG).

The dual connectivity means that the UE can be connected to both aMaster eNode-B (MeNB) and a Secondary eNode-B (SeNB) at the same time.The MCG is a group of serving cells associated with the MeNB, comprisingof a PCell and optionally one or more SCells. And the SCG is a group ofserving cells associated with the SeNB, comprising of the special SCelland optionally one or more SCells. The MeNB is an eNB which terminatesat least S1-MME (S1 for the control plane) and the SeNB is an eNB thatis providing additional radio resources for the UE but is not the MeNB.

With dual connectivity, some of the data radio bearers (DRBs) can beoffloaded to the SCG to provide high throughput while keeping schedulingradio bearers (SRBs) or other DRBs in the MCG to reduce the handoverpossibility. The MCG is operated by the MeNB via the frequency of f1,and the SCG is operated by the SeNB via the frequency of f2. Thefrequency f1 and f2 may be equal. The backhaul interface (BH) betweenthe MeNB and the SeNB is non-ideal (e.g. X2 interface), which means thatthere is considerable delay in the backhaul and therefore thecentralized scheduling in one node is not possible.

In the Dual Connectivity system, the buffer status reporting procedureis used to provide the serving eNB with information about the amount ofdata available for transmission in the UL buffers associated with theMAC entity. For the buffer status reporting procedure, the MAC entitymay consider all radio bearers which are not suspended and may considerradio bearers which are suspended. In this case, buffer status reportingis performed as MAC entity unit. Thus, the each MAC entity operatesindependently.

If the UE is configured with a Master Cell Group (MCG) and SecondaryCell Group (SCG), the procedures described below are applied to the MCGand SCG, respectively. When the procedures are applied to a SCG, theterm primary cell refers to the primary SCell (PSCell) of the SCG.

If the UE is configured with a PUCCH SCell, the procedures are appliedto the group of DL cells associated with the primary cell and the groupof DL cells associated with the PUCCH SCell, respectively. When theprocedures are applied to the group of DL cells associated with thePUCCH SCell, the term primary cell refers to the PUCCH SCell.

A DCI transports downlink, uplink or sidelink scheduling information,requests for aperiodic CQI reports, LAA common information,notifications of MCCH change or uplink power control commands for onecell and one RNTI. The RNTI is implicitly encoded in the CRC. Theprocessing structure for one DCI may include (i) Information elementmultiplexing, (ii) CRC attachment, (iii) Channel coding, and (iv) Ratematching.

The fields defined in the DCI formats below are mapped to theinformation bits α₀ to α_(A-1) as follows.

Each field is mapped in the order in which it appears in thedescription, including the zero-padding bit(s), if any, with the firstfield mapped to the lowest order information bit a₀ and each successivefield mapped to higher order information bits. The most significant bitof each field is mapped to the lowest order information bit for thatfield, e.g. the most significant bit of the first field is mapped to a₀.

DCI format 0 is used for the scheduling of PUSCH in one UL cell. Thefollowing information is transmitted by means of the DCI format 0.

-   -   Carrier indicator—0 or 3 bits.    -   Flag for format0/format1A differentiation—1 bit, where value 0        indicates format 0 and value 1 indicates format 1A.    -   Frequency hopping flag—1 bit. This field is used as the MSB of        the corresponding resource allocation field for resource        allocation type 1.    -   Resource block assignment and hopping resource        allocation—┌log₂(N_(RB) ^(UL)(N_(RB) ^(UL)+1)/2┐ bits. For PUSCH        hopping (resource allocation type 0 only), N_(UL_hop) MSB bits        are used to obtain the value of ñ_(PRB) ^((i)) and (┌log₂(N_(RB)        ^(UL)(N_(RB) ^(UL)+1)/2┐−N_(UL_hop) bits provide the resource        allocation of the first slot in the UL subframe. For non-hopping        PUSCH with resource allocation type 0, (┌log₂(N_(RB)        ^(UL)(N_(RB) ^(UL)+1)/2┐) bits provide the resource allocation        in the UL subframe. For non-hopping PUSCH with resource        allocation type 1, the concatenation of the frequency hopping        flag field and the resource block assignment and hopping        resource allocation field provides the resource allocation field        in the UL subframe.    -   Modulation and coding scheme and redundancy version—5 bits.    -   New data indicator—1 bit.    -   TPC command for scheduled PUSCH—2 bits.    -   Cyclic shift for DM RS and OCC index—3 bits.    -   UL index—2 bits, this field is present only for TDD operation        with uplink-downlink configuration 0.    -   Downlink Assignment Index (DAI)—2 bits, this field is present        only for cases with TDD primary cell and either TDD operation        with uplink-downlink configurations 1-6 or FDD operation.    -   CSI request—1, 2 or 3 bits. The 2-bit field applies to UEs        configured with no more than five DL cells and to (i) UEs that        are configured with more than one DL cell and when the        corresponding DCI format is mapped onto the UE specific search        space given by the C-RNTI, (ii) UEs that are configured by        higher layers with more than one CSI process and when the        corresponding DCI format is mapped onto the UE specific search        space given by the C-RNTI, or (iii) UEs that are configured with        two CSI measurement sets by higher layers with the parameter        csi-MeasSubframeSet, and when the corresponding DCI format is        mapped onto the UE specific search space given by the C-RNTI.        The 3-bit field applies to UEs that are configured with more        than five DL cells and when the corresponding DCI format is        mapped onto the UE specific search space given by the C-RNTI.        Otherwise, the 1-bit field applies.    -   SRS request—0 or 1 bit. This field can only be present in DCI        formats scheduling PUSCH which are mapped onto the UE specific        search space given by the C-RNTI.    -   Resource allocation type—1 bit. This field is only present if        N_(RB) ^(UL)≤N_(RB) ^(DL).

If the number of information bits in format 0 mapped onto a given searchspace is less than the payload size of format 1A for scheduling the sameserving cell and mapped onto the same search space (including anypadding bits appended to format 1A), zeros shall be appended to format 0until the payload size equals that of format 1A.

There is one HARQ entity at the MAC entity for each Serving Cell withconfigured uplink, which maintains a number of parallel HARQ processesallowing transmissions to take place continuously while waiting for theHARQ feedback on the successful or unsuccessful reception of previoustransmissions.

At a given TTI, if an uplink grant is indicated for the TTI, the HARQentity identifies the HARQ processes for which a transmission shouldtake place. It also routes the received HARQ feedback (ACK/NACKinformation), MCS and resource, relayed by the physical layer, to theappropriate HARQ processes.

For each TTI, the HARQ entity shall identify the HARQ process(es)associated with this TTI, and for each identified HARQ process, the MACentity shall obtain the MAC PDU to transmit from the Msg3 buffer ifthere is a MAC PDU in the Msg3 buffer and the uplink grant was receivedin a Random Access Response, deliver the MAC PDU and the uplink grantand the HARQ information to the identified HARQ process, and instructthe identified HARQ process to trigger a new transmission, if the uplinkgrant was received on PDCCH.

Each HARQ process is associated with a HARQ buffer.

Each HARQ process shall maintain a state variable CURRENT_TX_NB, whichindicates the number of transmissions that have taken place for the MACPDU currently in the buffer, and a state variable HARQ_FEEDBACK, whichindicates the HARQ feedback for the MAC PDU currently in the buffer.When the HARQ process is established, CURRENT_TX_NB shall be initializedto 0.

The sequence of redundancy versions is 0, 2, 3, 1. The variableCURRENT_IRV is an index into the sequence of redundancy versions. Thisvariable is up-dated modulo 4.

New transmissions are performed on the resource and with the MCSindicated on PDCCH or Random Access Response. Adaptive retransmissionsare performed on the resource and, if provided, with the MCS indicatedon PDCCH. Non-adaptive retransmission is performed on the same resourceand with the same MCS as was used for the last made transmissionattempt.

The MAC entity is configured with a Maximum number of HARQ transmissionsand a Maximum number of Msg3 HARQ transmissions by RRC: maxHARQ-Tx andmaxHARQ-Msg3Tx respectively. For transmissions on all HARQ processes andall logical channels except for transmission of a MAC PDU stored in theMsg3 buffer, the maximum number of transmissions shall be set tomaxHARQ-Tx. For transmission of a MAC PDU stored in the Msg3 buffer, themaximum number of transmissions shall be set to maxHARQ-Msg3Tx.

When the HARQ feedback is received for this TB, the HARQ process shallset HARQ_FEEDBACK to the received value.

If the HARQ entity requests a new transmission, the HARQ process shallset CURRENT_TX_NB to 0, set CURRENT_IRV to 0, store the MAC PDU in theassociated HARQ buffer, store the uplink grant received from the HARQentity, set HARQ_FEEDBACK to NACK, and generate a transmission asdescribed below.

If the HARQ entity requests a retransmission, the HARQ process shallincrement CURRENT_TX_NB by 1. If the HARQ entity requests an adaptiveretransmission, the HARQ process shall store the uplink grant receivedfrom the HARQ entity, set CURRENT_IRV to the index corresponding to theredundancy version value provided in the HARQ information, setHARQ_FEEDBACK to NACK, and generate a transmission as described below.Else if the HARQ entity requests a non-adaptive retransmission, ifHARQ_FEEDBACK=NACK, the HARQ process shall generate a transmission asdescribed below.

To generate a transmission, the HARQ process shall instruct the physicallayer to generate a transmission according to the stored uplink grantwith the redundancy version corresponding to the CURRENT_IRV value, andincrement CURRENT_IRV by 1 if the MAC PDU was obtained from the Msg3buffer; or if there is no measurement gap at the time of thetransmission and, in case of retransmission, the retransmission does notcollide with a transmission for a MAC PDU obtained from the Msg3 bufferin this TTI.

If there is a measurement gap at the time of the HARQ feedback receptionfor this transmission and if the MAC PDU was not obtained from the Msg3buffer, the HARQ process shall set HARQ_FEEDBACK to ACK at the time ofthe HARQ feedback reception for this transmission.

After performing above actions, the HARQ process then shall flush theHARQ buffer if CURRENT_TX_NB=maximum number of transmissions—1.

The Logical Channel Prioritization procedure is applied when a newtransmission is performed.

RRC controls the scheduling of uplink data by signalling for eachlogical channel: priority where an increasing priority value indicates alower priority level, prioritisedBitRate which sets the Prioritized BitRate (PBR), bucketSizeDuration which sets the Bucket Size Duration(BSD).

The MAC entity shall maintain a variable Bj for each logical channel j.Bj shall be initialized to zero when the related logical channel isestablished, and incremented by the product PBR×TTI duration for eachTTI, where PBR is Prioritized Bit Rate of logical channel j. However,the value of Bj can never exceed the bucket size and if the value of Bjis larger than the bucket size of logical channel j, it shall be set tothe bucket size. The bucket size of a logical channel is equal toPBR×BSD, where PBR and BSD are configured by upper layers.

The MAC entity shall perform the following Logical ChannelPrioritization procedure when a new transmission is performed. The MACentity shall allocate resources to the logical channels in the followingsteps.

Step 1: All the logical channels with Bj>0 are allocated resources in adecreasing priority order. If the PBR of a logical channel is set to“infinity”, the MAC entity shall allocate resources for all the datathat is available for transmission on the logical channel before meetingthe PBR of the lower priority logical channels.

Step 2: the MAC entity shall decrement Bj by the total size of MAC SDUsserved to logical channel j in Step 1.

Step 3: if any resources remain, all the logical channels are served ina strict decreasing priority order (regardless of the value of Bj) untileither the data for that logical channel or the UL grant is exhausted,whichever comes first. Logical channels configured with equal priorityshould be served equally.

The UE shall also follow the rules below during the schedulingprocedures above.

-   -   The UE should not segment an RLC SDU (or partially transmitted        SDU or retransmitted RLC PDU) if the whole SDU (or partially        transmitted SDU or retransmitted RLC PDU) fits into the        remaining resources of the associated MAC entity.    -   If the UE segments an RLC SDU from the logical channel, it shall        maximize the size of the segment to fill the grant of the        associated MAC entity as much as possible.    -   The UE should maximize the transmission of data.    -   if the MAC entity is given an UL grant size that is equal to or        larger than 4 bytes while having data available for        transmission, the MAC entity shall not transmit only padding BSR        and/or padding (unless the UL grant size is less than 7 bytes        and an AMD PDU segment needs to be transmitted).

The MAC entity shall not transmit data for a logical channelcorresponding to a radio bearer that is suspended.

For the Logical Channel Prioritization procedure, the MAC entity shalltake into account the following relative priority in decreasing order.

-   -   MAC control element for C-RNTI or data from UL-CCCH;    -   MAC control element for BSR, with exception of BSR included for        padding;    -   MAC control element for PHR, Extended PHR, or Dual Connectivity        PHR;    -   MAC control element for Sidelink BSR, with exception of Sidelink        BSR included for padding;    -   data from any Logical Channel, except data from UL-CCCH;    -   MAC control element for BSR included for padding;    -   MAC control element for Sidelink BSR included for padding.

When the MAC entity is requested to transmit multiple MAC PDUs in oneTTI, steps 1 to 3 and the associated rules may be applied either to eachgrant independently or to the sum of the capacities of the grants. Alsothe order in which the grants are processed is left up to UEimplementation. It is up to the UE implementation to decide in which MACPDU a MAC control element is included when MAC entity is requested totransmit multiple MAC PDUs in one TTI. When the UE is requested togenerate MAC PDU(s) in two MAC entities in one TTI, it is up to UEimplementation in which order the grants are processed.

In LTE, when the UE wants to transmit data in uplink, the UE request ULgrant by transmitting buffer status report to the eNB. Based on thebuffer status report from the UE, the eNB may allocate UL grant to theUE via PDCCH signaling. The PDCCH includes various DCI using variousformats. For example, the DCI format 0 may be used to allocate an ULgrant to the UE.

The problem in the prior art is that an UL grant is allocated for allRBs of a UE, and it cannot be guaranteed that the UE uses the receivedUL grant for a specific RB. For fine control of RB scheduling, amechanism to use UL grant only for a specific logical channel group(LCG) needs to be considered. The Logical Channel Group (LCG) is a groupof logical channels whose data available for transmission are reportedin BSR as a one group.

FIG. 7 is a diagram for transmitting data according to an embodiment ofthe present invention.

Referring to FIG. 7, the UE may receive a uplink grant for logicalchannel group (LCG) and a LCG indicator of the LCG (S710). In order forUE to use UL grant for a specific LCG, the eNB may indicate which LCG ofthe UE shall use the UL grant when the eNB allocates an UL grant to aUE.

For the signaling of UL grant and LCG indicator, the UE may receive ULgrant and LCG indicator as shown in the following examples.

As an example, the uplink grant and the LCG indicator are receivedthrough a Downlink Control Information (DCI) included in a PhysicalDownlink Control Channel (PDCCH). For example, in the prior art, ULgrant may be included in the DCI format 0 (i.e. resource blockassignment and hopping resource allocation). However, in this example,the LCG indicator may also be included in the DCI format 0. The lengthof the LCG indicator field should be able to indicate the maximum numberof LCGs that one UE supports. In LTE, the maximum number of LCGs is 4,and the LCG indication field should be 2 bits in this case.

For example, the DCI further includes uplink grant for another radiobearer and a radio bearer indicator of another radio bearer. In otherword, multiple sets of UL grant and LCG indicator may be included in theDCI of the PDCCH to allocate multiple UL grants via one PDCCH signaling.For this, The DCI may be extended to include multiple sets. In thiscase, when the UE receives at least one set of UL grant and LCGindicator, the UE may generate multiple PDUs for each LCG, and transmitsthem using the respective UL grants.

As the number of available bits in PDCCH is limited, multiple sets of ULgrant and LCG indicator may not be included in one PDCCH. As anotherexample for solving this problem, the uplink grant and the LCG indicatormay be received through a downlink MAC PDU included in a PhysicalDownlink Shared Channel (PDSCH).

In this case, the UE may receive a DCI indicating the PDSCH through aPhysical Downlink Control Channel (PDCCH). The PDCCH indicates PDSCH andthe downlink MAC PDU transmitted on the PDSCH may include one or more ULgrants and LCG indicators. For example, DCI formats 1, 2, 3, 4, 5, 6 maybe used for indicating the PDSCH. In addition, a special indication maybe added in those DCI formats to indicate that the corresponding PDSCHincludes UL grant and LCG indicator. For another example, a new DCIformat may be used to indicate PDSCH including UL grant and LCGindicator.

In addition, the uplink grant and the LCG indicator may be included inthe downlink MAC PDU as a MAC control element (CE). For example, an LCIDmay be allocated for the UL grant MAC CE and one UL grant MAC CE mayinclude one set of UL grant and LCG indicator. For another example, oneUL grant MAC CE may include multiple sets of UL grant and LCG indicator.

When the UE receives an UL grant and LCG indicator, the UE may generatea Medium Access Control Protocol Data Unit (MAC PDU) containing a dataof only the LCG indicated by the LCG indicator (S720). Subsequently, theUE may transmit the MAC PDU using the uplink grant (S730).

FIG. 8 is a block diagram of a communication apparatus according to anembodiment of the present invention.

The apparatus shown in FIG. 8 can be a user equipment (UE) and/or eNBadapted to perform the above mechanism, but it can be any apparatus forperforming the same operation.

As shown in FIG. 8, the apparatus may comprise a DSP/microprocessor(110) and RF module (transceiver; 135). The DSP/microprocessor (110) iselectrically connected with the transceiver (135) and controls it. Theapparatus may further include power management module (105), battery(155), display (115), keypad (120), SIM card (125), memory device (130),speaker (145) and input device (150), based on its implementation anddesigner's choice.

Specifically, FIG. 8 may represent a UE comprising a receiver (135)configured to receive a request message from a network, and atransmitter (135) configured to transmit the transmission or receptiontiming information to the network. These receiver and the transmittercan constitute the transceiver (135). The UE further comprises aprocessor (110) connected to the transceiver (135: receiver andtransmitter).

Also, FIG. 8 may represent a network apparatus comprising a transmitter(135) configured to transmit a request message to a UE and a receiver(135) configured to receive the transmission or reception timinginformation from the UE. These transmitter and receiver may constitutethe transceiver (135). The network further comprises a processor (110)connected to the transmitter and the receiver. The processor (110) isconfigured to perform operations according to the embodiment of thepresent invention exemplarily described with reference to theaccompanying drawings. In particular, the detailed operations of theprocessor (110) can refer to the contents described with reference toFIGS. 1 to 7.

The embodiments of the present invention described herein below arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It is obvious tothose skilled in the art that claims that are not explicitly cited ineach other in the appended claims may be presented in combination as anembodiment of the present invention or included as a new claim bysubsequent amendment after the application is filed.

In the embodiments of the present invention, a specific operationdescribed as performed by the BS may be performed by an upper node ofthe BS. Namely, it is apparent that, in a network comprised of aplurality of network nodes including a BS, various operations performedfor communication with an MS may be performed by the BS, or networknodes other than the BS. The term ‘eNB’ may be replaced with the term‘fixed station’, ‘Node B’, ‘Base Station (BS)’, ‘access point’, etc.

The above-described embodiments may be implemented by various means, forexample, by hardware, firmware, software, or a combination thereof.

In a hardware configuration, the method according to the embodiments ofthe present invention may be implemented by one or more ApplicationSpecific Integrated Circuits (ASICs), Digital Signal Processors (DSPs),Digital Signal Processing Devices (DSPDs), Programmable Logic Devices(PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers,microcontrollers, or microprocessors.

In a firmware or software configuration, the method according to theembodiments of the present invention may be implemented in the form ofmodules, procedures, functions, etc. performing the above-describedfunctions or operations. Software code may be stored in a memory unitand executed by a processor. The memory unit may be located at theinterior or exterior of the processor and may transmit and receive datato and from the processor via various known means.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from essential characteristics of the presentinvention. The above embodiments are therefore to be construed in allaspects as illustrative and not restrictive. The scope of the inventionshould be determined by the appended claims, not by the abovedescription, and all changes coming within the meaning of the appendedclaims are intended to be embraced therein.

What is claimed is:
 1. A method for transmitting, by a user equipment(UE), data in a wireless communication system, the method comprising:receiving a first uplink grant for a logical channel group (LCG) and afirst LCG indicator of the LCG, wherein the LCG is included in aplurality of LCGs having available data for transmission; generating aMedium Access Control Protocol Data Unit (MAC PDU) containing only dataof the LCG indicated by the first LCG indicator; performing a logicalchannel prioritization procedure based on the data of the LCG containedin the MAC PDU; and transmitting the MAC PDU using the first uplinkgrant, wherein the first uplink grant and the first LCG indicator arereceived through a Downlink Control Information (DCI) included in aPhysical Downlink Control Channel (PDCCH), and wherein the DCI furtherincludes a second uplink grant for another LCG and a second LCGindicator of the another LCG.
 2. A user equipment (UE) in a wirelesscommunication system, the UE comprising: a transmitter and a receiver;and a processor, operatively coupled to the transmitter and thereceiver, wherein the processor is configured to: control the receiverto receive a first uplink grant for a logical channel group (LCG) and afirst LCG indicator of the LCG, wherein the LCG is included in aplurality of LCGs having available data for transmission; generate aMedium Access Control Protocol Data Unit (MAC PDU) containing only dataof the LCG indicated by the first LCG indicator, perform a logicalchannel prioritization procedure based on the data of the LCG containedin the MAC PDU, and control the transmitter to transmit the MAC PDUusing the first uplink grant, wherein the first uplink grant and thefirst LCG indicator are received through a downlink MAC PDU included ina Physical Downlink Shared Channel (PDSCH).
 3. A user equipment (UE) ina wireless communication system, the UE comprising: a transmitter and areceiver; and a processor, operatively coupled to the transmitter andthe receiver, wherein the processor is configured to: control thereceiver to receive a first uplink grant for a logical channel group(LCG) and a first LCG indicator of the LCG, wherein the LCG is includedin a plurality of LCGs having available data for transmission, generatea Medium Access Control Protocol Data Unit (MAC PDU) containing onlydata of the LCG indicated by the first LCG indicator, perform a logicalchannel prioritization procedure based on the data of the LCG containedin the MAC PDU, and control the transmitter to transmit the MAC PDUusing the first uplink grant, wherein the first uplink grant and thefirst LCG indicator are received through a downlink MAC PDU included ina Physical Downlink Shared Channel (PDSCH), and wherein the first uplinkgrant and the first LCG indicator are included in the downlink MAC PDUas a MAC control element (CE).
 4. A method for transmitting, by a userequipment (UE), data in a wireless communication system, the methodcomprising: receiving a first uplink grant for a logical channel group(LCG) and a first LCG indicator of the LCG, wherein the LCG is includedin a plurality of LCGs having available data for transmission;generating a Medium Access Control Protocol Data Unit (MAC PDU)containing only data of the LCG indicated by the first LCG indicator;performing a logical channel prioritization procedure based on the dataof the LCG contained in the MAC PDU; and transmitting the MAC PDU usingthe first uplink grant, wherein the first uplink grant and the first LCGindicator are received through a downlink MAC PDU included in a PhysicalDownlink Shared Channel (PDSCH).